In situ observation of thermal runaway propagation in lithium-ion battery electrodes triggered by high-frequency induction heating

Lithium-ion batteries (LIBs) are instrumental for electric vehicles, but safety is a concern due to thermal runaway (TR) events. In this study, an in situ observation method for TR and its propagation (TRP) in LIB electrodes is presented, employing high-frequency induction heating as the TR triggering method. The non-contact, rapid heating technique facilitates direct trigger of TRP in a self-made tempered glass observer. Experiments reveal that venting occurs in all samples, and dendritic burn patterns appear on separators upon TRP. The heat-induced shrinkage of separators is more pronounced on the anode side. Phenomena observed during tests include gas flow paths, drifting sparks, short-circuit propagation, and electrolyte boiling. This method may contribute to a better understanding of LIB TRP behavior, facilitating strategies to improve safety and TR characteristics.